两个平面和之间的夹角是。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/5e5358c14af94be09327703e5cce7715.pnghttp://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/af5ae0cd0fcc4cdcbb23eec5cb652a80.png

设http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/6e6de13adf014e1f9fdc7954cb313377.png是由方程http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/6d1ea7ec74bb4607aee50aa325108197.png确定，求http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/1d60e0ceb7d14d26a00863c192e0bbf3.png（    ）

设http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/90c19a717ac34717836dbca4afba1bd9.png是由方程http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/7648e783c2f24044bb84346d0e07e161.png确定，求http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/d24ed3aef9a94d38965289947da528f7.png（     ）

下列函数中为奇函数的是( ) A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/7d0e4f5547744249b8c4c0e6db0e62fc.png"> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/d19abeb7724248dca0a0c1b8017897db.png"> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/3f5cff0b4a9b441da3b9e75bd446c141.png"> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/d59a9db29be640a899356a3f1645a0dd.png">

下列化合物能发生Hoffmann重排反应的是（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/48290165247643e1aac1067c27f0cfce.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/04103b28f4ec4c5f8d28d8f8392e143f.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/80cb1b0a7023476496199ba53a5f28f3.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/72d151e6a82943c6b11abdffa60b68c0.png" />